PROJECT SUMMARY Sleep deprivation in American youth is a major public health problem. Many youth experience insufficient and poor quality sleep, which can impair mental and physical health and cognitive- academic achievement. Significant gaps in this research include scarce investigations of long- term developmental trajectories of adaptation and maladaptation associated with objectively assessed sleep disturbances in youth. Furthermore, understanding the socioeconomic context of children?s sleep remains a critical gap in the field. Indeed, understanding mechanisms that explain health disparities as well as factors that prevent or protect against health disparities are high scientific priorities (Healthy People 2020). The proposed study addresses these gaps and advances parent grant discoveries. The design builds on a well-characterized 3-wave study and involves 3 additional waves. The sample consists of 355 youth (15-16 years at the fourth study wave) from semi-rural Alabama, with a high representation of African Americans and economic adversity. Strengths of the design include the large and diverse sample, breadth of measurement across important outcome domains, and 6 study waves, permitting analyses of long-term trajectories of mental health, physical health, autonomic nervous system activity, and cognitive-academic functioning in the context of health disparities. Constructs are assessed with multiple measures and informants. Sleep is examined objectively, via actigraphy, and subjectively. Autonomic nervous system activity is measured with well-established indices and procedures. The study will advance understanding of sleep in youth, by examining sleep variables that explain, exacerbate, or attenuate the negative effects of socioeconomic and racial health disparities (PA-13-292, Behavioral and Social Science Research on Understanding and Reducing Health Disparities; PA-14-033, Reducing Health Disparities among Minority and Underserved Children), and by examining outcomes identified as public health priorities, including mental health, physical health, academic performance, and stress response systems. We will address sleep processes across a wide range of social-ecological risk, thereby allowing tests of interactions and generalization to diverse children. Findings will illuminate sleep, behavioral, and ecological targets for intervention.